Erratum

1970 ◽  
Vol 52 (2) ◽  
pp. 494-494
Keyword(s):  
Fresh Water ◽  
Sodium Transport ◽  
Sodium Concentration ◽  
Sodium Influx ◽  
Lampetra Planeri

MORRIS, R. & BULL, J. M. Studies on fresh water osmoregulation in the Ammocoete larvae of Lampetra planeri Bloch. III. The effect of external and internal sodium concentration on sodium transport. J. Exp. Biol. 52, 2, pp. 275-290. Page 287. Figure 5. For ‘Sodium influx (µM/gm./hr.)’ read ‘Sodium influx (µM/3gm./hr.)’

Ionic Regulation of the Baltic and Fresh-Water Races of the Isopod Mesidotea (Saduria) Entomon (L.)

1968 ◽  
Vol 48 (1) ◽  
pp. 141-158 ◽  
Author(s):  
P. C. CROGHAN ◽  
A. P. M. LOCKWOOD
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Sodium Concentration ◽  
Relative Volume ◽  
Ice Age ◽  
Ionic Regulation ◽  
Sodium Influx ◽  
Active Uptake ◽  
Concentrated Solution ◽  
The Baltic

1. The isopod Mesidotea entomon has colonized the Baltic and certain Swedish lakes since the end of the last Ice Age. 2. The ionic regulation of Baltic animals and fresh-water animals (L. Mälaren) has been compared. 3. It has been possible to adapt Baltic animals to very dilute media, but 5% Askö sea water (5.5 mM/l. Na) appears to be the limit of adaptation. The haemolymph sodium concentration of Baltic animals from the very dilute media was considerably lowered. 4. The haemolymph sodium concentration in Mälaren animals is high (250 mM/l. Na) and comparable with that in Baltic animals in much more concentrated solution. The haemolymph ionic ratios of the Baltic and freshwater animals are similar. The Cl:Na ratio rises slightly in the more concentrated haemolymph samples. 5. From the concentration of ions in the haemolymph and in the total body water, the relative volume of the haemolymph was calculated. Mälaren animals appear to have a much larger haemolymph volume. 6. The permeability of the animals was determined from the rate of loss of sodium into de-ionized water. The permeability of the Mälaren animals is considerably reduced compared to the Baltic animals. Permeability is not related to the medium to which the animals had been adapted. 7. The sodium influx was determined using 22Na. The rate of active uptake was calculated from this. The maximal rate of active uptake was similar in Baltic and Mälaren animals. The sodium concentration of the medium at which active uptake was half maximum (KM) was considerably lower in Malaren animals than in Baltic animals. 8. The evolution of Mesidotea as a fresh-water animal is interpreted as a result of a reduction in permeability of the external surfaces to NaCl and an increase in the affinity of the active transport mechanism enabling the animal to maintain the haemolymph NaCl concentration in a steady state in fresh water.

Studies on Fresh-Water Osmoregulation in the Ammocoete Larva of Lampetra Planeri (Bloch)

1970 ◽  
Vol 52 (2) ◽  
pp. 275-290
Author(s):  
R. MORRIS ◽  
J. M. BULL
Keyword(s):  
Sodium Concentration ◽  
Sodium Balance ◽  
Sodium Influx ◽  
Environmental Concentration ◽  
Carrier Mechanism ◽  
Controlling Mechanism ◽  
Lampetra Planeri ◽  
Reverse Situation ◽  
Sodium Loss ◽  
Term Response

1. Sodium influx in ammocoete larvae increases exponentially with external sodium concentration (0-1.0 mM/l.) and sodium-depleted animals show a 20% increase compared with normal animals. 2. Sodium loss decreases as the environmental concentration decreases, although the reverse situation is expected from considering diffusion outflux alone. 3. It is argued that part of the sodium loss is back-transported by the transport mechanism and this accounts for the reduced sodium loss from sodium-depleted animals whose sodium carrier activity is increased. The curves relating back-transport to environmental sodium differ from those derived by Kirschner for isolated frog skin. 4. Sodium influx increases as sodium loss increases, indicating a self mechanism whose features are discussed. In the ammocoete, the sodium carrier mechanism appears to change in affinity for sodium (short-term response) and can also change in concentration (long-term response), and it is suggested that these features, together with permeability changes, may form the basis of the controlling mechanism for sodium balance.

Sodium Regulation in the Fresh-Water Amphipod, Gammarus Pulex (L.)

1967 ◽  
Vol 46 (3) ◽  
pp. 499-518
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Loss Rate ◽  
Sodium Concentration ◽  
The Body ◽  
Uptake Mechanism ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
Sodium Loss ◽  
Total Sodium

1. Sodium influx and loss rates in Gammarus pulex were measured at constant temperatures. The sodium loss rate was immediately influenced by a change in temperature, with a Q10 of 1.5 to 2.0 at temperatures between 0.3 and 21.5° C. The sodium influx rate is apparently influenced in the same way. 2. The sodium uptake mechanism in G. pulex from three localities was half-saturated at an external concentration of 0.10-0.15 mM/l. sodium. 3. The total sodium loss rate remained approximately constant in animals acclimatized to the range of external concentrations from 2 to about 0.2 mM/l. sodium. 18% of the sodium was lost in urine with a sodium concentration estimated at 30-50 mM/l. The remainder of the sodium loss was due to diffusion across the body surface. 4. In animals acclimatized to concentrations below about 0.2 mM/l. sodium the sodium loss rate was reduced, due to (a) a lower diffusion rate following a fall in the blood sodium concentration, and (b) the elaboration of a more dilute urine. 5. There was a very close association between changes in the blood sodium concentration, the elaboration of a very dilute urine, and the rate of sodium uptake at the body surface. The results indicate that a fall in the blood sodium concentration leads to simultaneous activation of the sodium uptake mechanisms at the body surface and in the antennary glands. 6. It is estimated that, by producing a dilute urine, total sodium uptake in G. pulex is shared equally between the renal uptake mechanism and the mechanism situated at the body surface. 7. In sea-water media G. pulex drinks and expels fluid from the gut. In a medium slightly hyperosmotic to the normal blood concentration the amount imbibed was equal to the normal rate of urine flow when in fresh water.

Changes of sodium transport in erythrocytes of the maturing rabbit

1975 ◽  
Vol 228 (2) ◽  
pp. 461-464 ◽  
Author(s):  
EK Smith ◽  
L Weihrauch ◽  
D Farrington
Keyword(s):  
Atpase Activity ◽  
Sodium Transport ◽  
Sodium Concentration ◽  
Red Cells ◽  
Potassium Content ◽  
High Potassium ◽  
Sodium Influx ◽  
Sodium Efflux ◽  
Low Sodium ◽  
Total Sodium

The red blood cells of New Zealand white rabbits have a low sodium and high potassium content. As the animals mature, the sodium concentration rises and the potassium content falls; studies of red cells from a group of five young and five mature animals revealed a highly significant increase of cell sodium with age that was associated with a significant fall in the rate of ouabain-inhibited active sodium efflux. This difference was still seen when the sodium concentration within the cells from old and young animals was equalized and elevated to saturating levels for active pump efflux. Total sodium efflux, however, increased significantly with age as did total sodium influx so that a steady state was reached. Ouabain-sensitive ATPase activity fell significantly in the cell membranes from older animals and ouabain-insensitive ATPase increased with age. The survival time of 51Cr-labeled red cells was significantly longer in old than in young animals and it is concluded that as the rabbit matures its red cells survive for a longer period and this is associated with the changes of sodium transport and ATPase activity that have been documented.

The Sodium Balance Mechanism in the Fresh-Water Amphipod, Gammarus Lagustris Sars

1967 ◽  
Vol 46 (3) ◽  
pp. 519-528
Author(s):  
D. W. SUTCLIFFE ◽  
J. SHAW
Keyword(s):  
Fresh Water ◽  
Loss Rate ◽  
Sodium Concentration ◽  
The Body ◽  
Sodium Balance ◽  
External Concentration ◽  
Sodium Influx ◽  
Influx Rate ◽  
Sodium Loss ◽  
Balance Mechanism

1. The sodium balance mechanism of Gammarus lacustris in fresh water is virtually identical with that found in G. pulex. 2. The sodium transporting system at the body surface has a very high affinity for sodium ions. The system is half-saturated at an external concentration of about 0.14 mM/l. and fully saturated at about 1 mM/l. sodium. 3. The lowest external concentration at which sodium balance was maintained was 0.06 mM/l. 4. Both the total sodium loss rate and the sodium influx rate remained approximately constant in animals acclimatized to the range of external concentrations from 2 to 0.3 mM/l. NaCl. At lower concentrations the loss rate was reduced and the influx increased by a factor of about 1.5. 5. Changes in the sodium influx and loss rates are very closely linked together, and it is shown how these changes are related to the external sodium concentration.

The change from symmetry to asymmetry of a sodium transport system in red cell membranes

1985 ◽  
Vol 223 (1233) ◽  
pp. 449-457 ◽  
Keyword(s):  
Sodium Concentration ◽  
Tracer Studies ◽  
Chloride Medium ◽  
Sodium Influx ◽  
Nitrate Medium ◽  
Sodium Efflux ◽  
External Potassium ◽  
Red Cell Membranes ◽  
Stimulation Of ◽  
Human Red Cells

A study has been made with human red cells of sodium movements that are sensitive to the drug furosemide. The aim was to see if furosemide-sensitive movements that are symmetrical (exchange) became asymmetrical (net transport) on replacement of chloride with nitrate as the major external anion. Cells were incubated for 4 h at 37 °C with 140 mm sodium, and chloride or nitrate as the principal anion. Under a variety of conditions (presence and absence of ouabain or furosemide, or both) the cell sodium concentration was always higher when chloride was replaced with nitrate. The cells became leakier to sodium. Tracer studies indicated that, in contrast to the results in chloride medium, the decrease in sodium influx was greater than the fall in efflux when furosemide was added to cells in nitrate medium. The results confirm that the sensitivity of sodium efflux to furosemide depended on chloride. However, influx showed a different sensitivity in that furosemide still inhibited in cells incubated in nitrate medium. The stimulation of sodium influx with nitrate medium was independent of external potassium (10–50 mm) and the furosemide-sensitive influx was also constant. It is concluded that symmetrical transmembrane sodium movements with cells in chloride medium became downhill asymmetrical in nitrate medium, giving a net gain of cell sodium that was insensitive to ouabain and sensitive to furosemide. The drug thus partly retarded the gain of cell sodium that otherwise occurred in the somewhat leaky cells.

Sodium Regulation in the Freshwater Mollusc Limnaea Stagnalis (L.) (Gastropoda: Pulmonata)

1970 ◽  
Vol 53 (1) ◽  
pp. 147-163 ◽  
Author(s):  
PETER GREENAWAY
Keyword(s):  
Blood Volume ◽  
Tap Water ◽  
Sodium Concentration ◽  
Sodium Balance ◽  
Uptake Mechanism ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
Limnaea Stagnalis ◽  
Total Body ◽  
Sodium Regulation

1. Sodium regulation in normal, sodium-depleted and blood-depleted snails has been investigated. 2. Limnaea stagnalis has a sodium uptake mechanism with a high affinity for sodium ions, near maximum influx occurring in external sodium concentrations of 1.5-2 mM-Na/l and half maximum influx at 0.25 mM-Na/l. 3. L. stagnalis can maintain sodium balance in media containing 0.025 mM-Na/l. Adaptation to this concentration is achieved mainly by an increased rate of sodium uptake and a fall of 37 % in blood sodium concentration, but also by a reduction of the sodium loss rate and a decrease in blood volume. 4. A loss of 23% of total body sodium is necessary to stimulate increased sodium uptake. This loss causes near maximal stimulation of the sodium uptake mechanism. 5. An experimentally induced reduction of blood volume in L. stagnalis increases sodium uptake to three times the normal level. 6. About 40% of sodium influx from artificial tap water containing 0.35 mM-Na/l into normal snails is due to an exchange component. Similar exchange components of sodium influx were also observed in sodium-depleted and blood-depleted snails in the same external sodium concentration.

Studies on Freshwater Osmoregulation in the Ammocoete larva of Lampetra Planeri (Bloch)

1968 ◽  
Vol 48 (3) ◽  
pp. 597-609
Author(s):  
R. MORRIS ◽  
J. M. BULL
Keyword(s):  
Low Temperature ◽  
Extracellular Space ◽  
Ringer Solution ◽  
Temperature Treatment ◽  
Sodium Influx ◽  
Sodium Chloride Solutions ◽  
Low Temperature Treatment ◽  
Lampetra Planeri ◽  
Equilibrium Concentrations ◽  
Sodium Loss

1. An investigation has been made of the factors which cause sodium loss from ammocoetes when they are immersed in de-ionized water at 1° and 10° C. 2. Sodium influx ceases when animals are first immersed in de-ionized water, but can recommence when the animal loses sufficient sodium to the environment. The concentration of sodium required for influx to take place decreases with succeeding periods of immersion in de-ionized water at 10° C. and reaches minimum equilibrium concentrations as low as 0.005 mM-Na/l. 3. Low temperature inhibits sodium influx and thus promotes net loss of sodium to de-ionized water. 4. Low temperature also decreases the initial loss of sodium to de-ionized water and probably lowers the permeability of the external surfaces of the animal to ions. This effect is small compared with the inhibition of ion uptake so that the combined result is to increase the net loss of sodium from the animal. 5. Since animals lose calcium to de-ionized water and show a decreased rate of sodium loss when calcium salts are added, it is believed that the high rates of sodium loss in de-ionized water are attributable to the effect of calcium on permeability. 6. Lack of calcium may also explain why animals which have been depleted of sodium by low-temperature treatment take up sodium much faster at higher temperatures from dilute Ringer solutions than from pure sodium chloride solutions. 7. When animals lose ions to de-ionized water at low temperature, sodium and chloride are lost from the extracellular space, whilst the muscle cells lose potassium. These ions are recovered into the extracellular space when animals are allowed to take up ions at 10° C. from diluted Ringer solution later.

Sodium Regulation and Adaptation to Fresh Water in Gammarid Crustaceans

1968 ◽  
Vol 48 (2) ◽  
pp. 359-380
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Body Weight ◽  
Fresh Water ◽  
Body Surface ◽  
Sea Water ◽  
Sodium Concentration ◽  
The Body ◽  
Outward Diffusion ◽  
Gammarus Zaddachi ◽  
Freshwater Habitats ◽  
Sodium Regulation

1. Sodium uptake and loss rates are given for three gammarids acclimatized to media ranging from fresh water to undiluted sea water. 2. In Gammarus zaddachi and G. tigrinus the sodium transporting system at the body surface is half-saturated at an external concentration of about 1 mM/l. and fully saturated at about 10 mM/l. sodium. In Marinogammarus finmarchicus the respective concentrations are six to ten times higher. 3. M. finmarchicus is more permeable to water and salts than G. zaddachi and G. tigrinus. Estimated urine flow rates were equivalent to 6.5% body weight/hr./ osmole gradient at 10°C. in M. finmarchicus and 2.8% body weight/hr./osmole gradient in G. zaddachi. The permeability of the body surface to outward diffusion of sodium was four times higher in M. finmarchicus, but sodium losses across the body surface represent at least 50% of the total losses in both M. finmarchicus and G. zaddachi. 4. Calculations suggest that G. zaddachi produces urine slightly hypotonic to the blood when acclimatized to the range 20% down to 2% sea water. In fresh water the urine sodium concentration is reduced to a very low level. 5. The process of adaptation to fresh water in gammarid crustaceans is illustrated with reference to a series of species from marine, brackish and freshwater habitats.

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